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Topic Review
Vesicular Systems for Advanced Drug Delivery
Erythromycin (ERY) is a macrolide compound with a broad antimicrobial spectrum which is currently being used to treat a large number of bacterial infections affecting the skin, respiratory tract, intestines, bones and other systems, proving great value from a clinical point of view. Despite this major advantage, ERY has low water solubility and is not stable under acidic conditions which leads to a limited efficacy and bioavailability. Apart from this, higher doses promote drug resistance and undesirable effects. In order to overcome these disadvantages, during the past decades, a large variety of ERY formulations, including nanoparticles, have emerged. This work presents the preparation and performances reported for ERY vesicles, such as liposomes, ethosomes, niosomes, micelles, cubosomes and solid lipid nano(micro) particles. 
  • 718
  • 19 Oct 2022
Topic Review
Chemical Bonding of H2O
Water (H2O) is a simple triatomic bent molecule with C2v molecular symmetry and bond angle of 104.5° between the central oxygen atom and the hydrogen atoms. Despite being one of the simplest triatomic molecules, its chemical bonding scheme is nonetheless complex as many of its bonding properties such as bond angle, ionization energy, and electronic state energy cannot be explained by one unified bonding model. Instead, several traditional and advanced bonding models such as simple Lewis and VESPR structure, valence bond theory, molecular orbital theory, isovalent hybridization, and Bent's rule are discussed below to provide a comprehensive bonding model for H2O, explaining and rationalizing the various electronic and physical properties and features manifested by its peculiar bonding arrangements.
  • 6.2K
  • 18 Oct 2022
Topic Review
Applications of Heterocyclic Compounds
Fluorescently labelled heterocyclic compounds are useful in bioanalytical applications, including in vivo imaging, high throughput screening, diagnostics, and light-emitting diodes. These compounds have various therapeutic properties, including antifungal, antitumor, antimalarial, anti-inflammatory, and analgesic activities. Different neutral fluorescent markers containing nitrogen heterocycles (quinolones, azafluoranthenes, pyrazoloquinolines, etc.) have several electrochemical, biological, and nonlinear optic applications. Photodynamic therapy (PDT), which destroys tumors and keeps normal tissues safe, works in the presence of molecular oxygen with light and a photosensitizing drugs (dye) to obtain a therapeutic effect. 
  • 6.0K
  • 18 Oct 2022
Topic Review
Benzodiazepine Use Disorder
Benzodiazepine use disorder (BUD), also called misuse or abuse, is the use of benzodiazepines without a prescription, often for recreational purposes, which poses risks of dependence, withdrawal and other long-term effects. Benzodiazepines are one of the more common prescription drugs used recreationally. When used recreationally benzodiazepines are usually administered orally but sometimes they are taken intranasally or intravenously. Recreational use produces effects similar to alcohol intoxication. In tests in pentobarbital trained rhesus monkeys benzodiazepines produced effects similar to barbiturates. In a 1991 study, triazolam had the highest self-administration rate in cocaine trained baboons, among the five benzodiazepines examined: alprazolam, bromazepam, chlordiazepoxide, lorazepam, triazolam. A 1985 study found that triazolam and temazepam maintained higher rates of self-injection in both human and animal subjects compared to a variety of other benzodiazepines (others examined: diazepam, lorazepam, oxazepam, flurazepam, alprazolam, chlordiazepoxide, clonazepam, nitrazepam, flunitrazepam, bromazepam, and clorazepate). A 1991 study indicated that diazepam, in particular, had a greater abuse liability among people who were drug abusers than did many of the other benzodiazepines. Some of the available data also suggested that lorazepam and alprazolam are more diazepam-like in having relatively high abuse liability, while oxazepam, halazepam, and possibly chlordiazepoxide, are relatively low in this regard. A 1991–1993 British study found that the hypnotics flurazepam and temazepam were more toxic than average benzodiazepines in overdose. A 1995 study found that temazepam is more rapidly absorbed and oxazepam is more slowly absorbed than most other benzodiazepines. Benzodiazepines have been abused both orally and intravenously. Different benzodiazepines have different abuse potential; the more rapid the increase in the plasma level following ingestion, the greater the intoxicating effect and the more open to abuse the drug becomes. The speed of onset of action of a particular benzodiazepine correlates well with the 'popularity' of that drug for abuse. The two most common reasons for preference were that a benzodiazepine was 'strong' and that it gave a good 'high'. According to Dr. Chris Ford, former clinical director of Substance Misuse Management in General Practice, among drugs of abuse, benzodiazepines are often seen as the 'bad guys' by drug and alcohol workers. Illicit users of benzodiazepines have been found to take higher methadone doses, as well as showing more HIV/HCV risk-taking behavior, greater poly-drug use, higher levels of psychopathology and social dysfunction. However, there is only limited research into the adverse effects of benzodiazepines in drug misusers and further research is needed to demonstrate whether this is the result of cause or effect.
  • 1.2K
  • 18 Oct 2022
Topic Review
Hexadehydro Diels-Alder Reaction
In organic chemistry, the hexadehydro-Diels-Alder (HDDA) reaction is an organic chemical reaction between a diyne (2 alkyne functional groups arranged in a conjugated system) and an alkyne to form a reactive benzyne species, via a [4+2] cycloaddition reaction. This benzyne intermediate then reacts with a suitable trapping agent to form a substituted aromatic product. This reaction is a derivative of the established Diels-Alder reaction and proceeds via a similar [4+2] cycloaddition mechanism. The HDDA reaction is particularly effective for forming heavily functionalized aromatic systems and multiple ring systems in one synthetic step.
  • 411
  • 18 Oct 2022
Topic Review
Three-finger Toxin
Three-finger toxins (abbreviated 3FTx) are a protein superfamily of small toxin proteins found in the venom of snakes. Three-finger toxins are in turn members of a larger superfamily of three-finger protein domains which includes non-toxic proteins that share a similar protein fold. The group is named for its common structure consisting of three beta strand loops connected to a central core containing four conserved disulfide bonds. The 3FP protein domain has no enzymatic activity and is typically between 60-74 amino acid residues long. Despite their conserved structure, three-finger toxin proteins have a wide range of pharmacological effects. Most members of the family are neurotoxins that act on cholinergic intercellular signaling; the alpha-neurotoxin family interacts with muscle nicotinic acetylcholine receptors (nAChRs), the kappa-bungarotoxin family with neuronal nAChRs, and muscarinic toxins with muscarinic acetylcholine receptors (mAChRs).
  • 641
  • 18 Oct 2022
Topic Review
The Structure and Preparation of Carbon Nanotubes
Materials are the basis of the evolution of human civilization. The pursuit of the ultimate properties of materials, such as super strength and super toughness, has strongly promoted the development of human culture. Carbon nanotubes (CNTs) with superior mechanical properties are expected to play a role in the next generation of critical engineering mechanical materials.
  • 427
  • 18 Oct 2022
Topic Review
List of Oxidation States of the Elements
This is a list of known oxidation states of the chemical elements, excluding nonintegral values. The most common states appear in bold. The table is based on that of Greenwood and Earnshaw, with additions noted. Oxidation state 0, which occurs for all elements, is implied by the column with the symbol of the element. The format of the table, which was devised by Dmitri Mendeleev in 1889, shows the periodicity of the oxidation states of the elements.
  • 13.1K
  • 18 Oct 2022
Topic Review
Raw Materials for Geopolymer Production
Due to the high generation of industrial waste by-products, disposal concerns, less utilization, and hazardous nature, the research on its valorization as a precursor for geopolymer production is potentially environmentally viable.
  • 1.3K
  • 18 Oct 2022
Topic Review
Metal–Organic Framework-Based Materials for Photocatalytic Nitrogen Fixation
Metal–organic frameworks (MOFs) are coordination polymers with high porosity that are constructed from molecular engineering. Constructing MOFs as photocatalysts for the reduction of nitrogen to ammonia is a newly emerging but fast-growing field, owing to MOFs’ large pore volumes, adjustable pore sizes, controllable structures, wide light harvesting ranges, and high densities of exposed catalytic sites. They are also growing in popularity because of the pristine MOFs that can easily be transformed into advanced composites and derivatives, with enhanced catalytic performance.
  • 690
  • 18 Oct 2022
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